1. Field of the Invention
This invention relates to surfactant mixtures with improved dermatological compatibility and advantageous low-temperature behavior which contain alkyl oligoglucosides having a selected chain length composition.
2. Statement of Related Art
Alkyl oligoglycosides, especially alkyl oligoglucosides, are nonionic surfactants which are acquiring increasing significance by virtue of their excellent detergent properties and their high ecotoxicological compatibility. The production and use of these substances have been described just recently in a number of synoptic articles of which the articles by H. Hensen in Skin Care Forum, 1, (October 1992), D. Balzer and N. Ripke in Seifen-Ole-Fette-Wachse 118, 894 (1992) and B. Brancq in Seifen-Ole-Fette-Wachse 118, 905 (1992) are cited as representative.
Although alkyl oligoglucosides are extremely mild on the skin, there is still a growing need for substances having further improved dermatological compatibility. For example, attempts have been made in the past to improve the dematological compatibility of alkyl oligoglucosides by addition of amphoteric surfactants.
A starting point for the production of particularly high-performance alkyl oligoglucosides is to mix species differing in their chain length. For example, it is proposed in hitherto unpublished patent application U.S. Ser. No. 07/876,967 (Henkel Corp.) to mix two alkyl oligoglucosides having chain lengths of C.sub.8-10 and C.sub.12-16 in a ratio of 50:50 to 90:10 parts by weight. However, this application teaches using a mixing ratio of 60:40 to 80:20, i.e. using the short-chain species in excess.
DE-A1 40 05 958 (Huls) describes a liquid foaming cleaning preparation which may contain 3 to 40% by weight of a C.sub.7-10 alkyl oligoglucoside and 3 to 40% by weight of a C.sub.11-18 alkyl oligoglucoside (ad 100% by weight water). It is proposed to use the relatively short-chain and relatively long-chain species in a ratio by weight of 10:90 to 50:50 and preferably in a ratio of 17:83 to 33:67. There is no reference in this document to particular advantages arising out of the dermatological compatibility of the mixture.
In the past, alkyl oligoglucosides differing in their chain length have been mixed primarily with a view to obtaining optimal performance properties. Although the mixtures according to the prior art may be satisfactory, for example, in regard to their foaming and cleaning power, their dermatological compatibility is not optimal.
Now, the problem addressed by the present invention was to provide new mixtures of alkyl oligoglucosides differing in their chain lengths which would be free from the disadvantages mentioned above.